Quantity measurement of fish in a trawl net



F. J. LUKETA 3,366,969

QUANTITY MEASUREMENT OF FISH IN A TRAWL NET Jan. 30, 1968 7 Sheets-Sheet1 Original Filed Aug. 31, 1964 INVENTOR FRANK rf UL/67A BY I ATTOP/Vz? JJan. 30, 1968 F. J. LUKETA 3,366,969

QUANTITY MEASUREMENT OF FISH IN A TRAWL NET Original Filed Aug. 31, 19647 Sheets-Sheet 2 INVETOR. FRANK r]: (J/(721 F. J. LUKETA 3,366,969

QUANTITY MEASUREMENT OF FISH IN A TRAWL. NET

' Jan.30, 1968 7 Sheets-Sheet .3 I

Original Filed Aug. 31, 1964 W M NM INVENTOR.

Jan. 30, 1968 F. J LUKETA 3,366,969

QUANTITY MEASUREMENT OF FISH IN A TRAWL NET Original Filed Aug. 31, 19647 Sheets-Sheet 4 INVENTOR. FRANK :Z Aux 5m I Jan. 30, 1968 F. J. LUKETAQUANTITY MEASUREMENT OF FISH IN A TRAWL NET Original Filed Aug. 51, 19647 Sheets-Sheet 5 INVENTOR. FRA /W( J (0x074 Jan. 30, 1968 F. J. LUKETA3,366,969

QUANTITY MEASUREMENT OF FISH IN A TRAWL: NET

Original Filed Aug. 31, 1964 7 Sheets-Sheet 6 INVENTOR. 57/ I FRANK a.AU/(EIA Jan. 30, 1968 v F. J. LUKETA 3,366,969

QUANTITY MEASUREMENT OF FISH IN A TRAWL, NET

Original Filed Aug. 51, 1964 7 Sheets-Sheet 7 A 0/1 D IND/CA roe AND/ weP56000512 a AO/ID w 6 067E670? -/04 2 92 6 DEW; INVENTOR.

ATTO/Q VIFY) United States Patent ABSTRACT (I THE DISCLOSURE Trawlingapparatus having load sensing line means connected to the codend of thetrawl net and extending forwardly therefrom to a load sensing meansmounted on a trawl door for deriving a signal based on the tension inthe load sensing line means caused by pressure of fish in the codend.The derived signal is transmitted to the trawler to indicate thequantity of fish in the net.

This application is a continuation of my now abandoned, copendingapplication, Ser. No. 489,793, entitled, Apparatus for Measuring theQuantity of Fish in a Trawl Net, and filed Sept. 7, 1965, as acontinuation of my now abandoned application Ser. No. 393,236 entitled,Method and Apparatus for Measuring the Quantity of Fish in a Trawl Net,and filed Aug. 31, 1964, as a continuation-inpart of my priorapplication Ser. No. 305,485, filed Aug. 29, 1963, as a continuation ofmy prior, now abandoned, application Ser. No. 52,141, filed Aug. 26,1960, the latter two applications both being entitled, Trawl Net LoadResponsive Apparatus and Method.

The present invention relates to trawling, and more particularly to anapparatus for determining the quantity of fish in the net from aboardthe trawler.

It is old to connect the forward ends of the towing warps of a trawl netto load sensing means situated aboard the trawler for the purpose ofmeasuring the increase in the total drag of the net assembly that isproduced by the fish being caught by the net, or by the net snagging onsome bottom obstacle. Systems of this general type are disclosed by US.Patent No. 2,079,021, issued May 4, 1937, to John C. Malcolm and RalphS. Symonds, and in US. Patent No. 2,513,153, issued June 27, 1950, toVito DIntino.

An entire trawl net assembly, even a relatively small one, produces anappreciable drag when empty. Beginning with the codend, the dragincreases with each net component forwardly of the codend-the curtainsand sweep lines, the doors and finally the towing warps. Each adds itsindividual drag to the total. As fish are added to the net, the totaldrag is increased, but not by an amount equal to the weight of such fishout of the Water. In fact, a full load of fish in the codend of a notwill increase the total drag of the entire net assembly by an amountwhich is relatively small in relation to the drag of the net assemblywhen the not proper is empty.

In systems of the type disclosed in the Malcolm et a1. patent, forexample, the increase in the total drag does not give the trawl operatora reliable indication of the quantity of fish in the net. This isbecause the drag produced by fish in the net is a relatively very smallpercentage of the total. Such total drag is a relatively large value andrequires the employment of a load indicating device that is capable ofrecording a relatively large force. In some cases, the portion of thetotal drag attributed to fish in the net, representing the increase indrag over and above the drag of the empty net and the other componentsof the net assembly, may be close in value to the error of the measuringinstrument. As a result the trawl operator is not given a reliableindication of the quantity of fish in the net.

This invention involves an apparatus for measuring only that portion ofthe total drag of the net that is produced by water and by fish in thenet pressing against the rear wall of the nets codend; deriving anelectrical signal based on such portion of the total drag; and thentransmitting such signal to receiving equipment situated aboard thetrawler whereat it is utilized to give the trawl operator a reliableindication of the quantity of fish in the net. By continuously readingand/or recording this signal during trawling the trawl operator can tellwhen and where the fish are being caught, and when the net is full andready to be hauled in.

Generally speaking, the load sensing equipment of the present inventioncomprises a load sensing device (eg a strain gage) mounted on a portionof the towing means for the net, such as one of the trawl doors, forexample; load sensing line means interconnecting between said loadsensing device and the pursed after terminal of the nets codend, withsaid load sensing device serving to measure the tension put into saidload sensing line means by reason of water and fish in the net pressingagainst the rear Wall of the codend and to derive an electrical signalbased on such tension; means for transmitting said signal to thetrawler; and means on the trawler for receiving and utilizing thesignal, such as a meter having a dial which can be read directly by theoperator, for example. The towing means for the net includes the sweeplines SL, the curtain lines 16, the doors 10, and the towing warps 12.

Preferably the load sensing line means is shorter in length than thenormal distance between the load sensing device and the pursed terminalof the not so that during trawling the after end portion of the codendis ulled outside in by the load sensing line means, and a generallyannular rear wall formed. As the fish press relatively rearwardlyagainst this rear wall there is a tendency for the pursed terminal ofthe codend to be displaced rearwardly to its normal position. Suchdisplacement is resisted, and to a large extent prevented, by the loadsensing line means, but the load sensing line means is put in tension,and the value of such tension is directly proportional to the force ordrag produced by the fish pressing against said rear wall.

These and other characteristics, features, objects and advantages of thepresent invention will be apparent from the following description ofcertain typical embodiments thereof, taken together with theaccompanying illustrations, wherein like letter designations and likenumerals refer to like parts, and wherein:

FIG. 1 is a perspective view presented as three related sections,illustrating a bottom trawl net layout, for sake of example, with thenet broken away in the region above a suspension bar and its associatedelements, such net incorporating a load sensing apparatus constructedand arranged according to the present invention;

FIG. 2 is an enlarged scale perspective view of the after portion of thenets codend, with the foreground netting cut away for sake of betterillustrating the pursed terminal of the codend;

FIG. 3 is a longitudinal sectional view of the after portion of saidcodend, with the forward boundary of a typical catch being indicated bya wavy broken line;

FIG. 4 is a reduced scale, side elevational view of the after portion ofthe trawl net;

FIG. 5 is a view similar to FIG. 4, but showing the tension relievedfrom the load line means;

FIG. 6 is a view of that portion of the net shown by FIGS 4 and 5, butshowing the after terminal of the codend open;

FIG. 7 is a longitudinal sectional view of the after portion of thecodend, with the after terminal shown in a partly open condition;

FIG. 8 is a cross-sectional view taken through the codend, lookingrearwardly toward the pursing mechanism which is shown in a partly opencondition, such view being taken substantially along line 8-8 of FIG. 7;

FIG. 9 is a view similar to FIG. 7, but showing the after terminal fullyopen;

FIG. 10 is a fragmentary, side elevational view of the codend taken inthe vicinity of the pursing mechanism, with such mechanism and thenetting to which it is attached being in the partly open condition shownby FIGS. 7 and 8;

FIG. 11 is a view like FIG. 10, but showing the netting and thecomponents of the pursing mechanism as they appear when the afterterminal is fully open;

FIG. 12 is a plan view of a trawl net assembly incorporating one form ofload sensing means constructed and arranged according to the presentinvention, with the forward portion of the net, and the doors, lines andtrawler ahead of the net, being shown in top plan, with the rear portionof the net being shown on an enlarged scale and in bottom plan, with theforward part of the codend being cut away for clarity of illustration,and with the loading sensing means including a load measuring devicemounted on one of the trawl doors;

FIG. 13 is a fragmentary, perspective view of the rearward portion ofthe net assembly shown in FIG. 12;

FIG. 14 is a top plan view of the trawl door which mounts the loadmeasuring device, with a portion of said door being broken away so as topresent a clear showing of a typical load measuring device;

FIG. 15 is a fragmented, top plan view of that portion of FIG. 14 in theimmediate vicinity of said load measuring device, but on a larger scalethan FIG. 14;

FIG. 16 is a fragmentary top plan view of that portion of FIG. 14 in theimmediate vicinity of the shackle device which connects the electricalconductor containing towing warp to the door bridle;

FIG. 17 is a side elevational view of the shackle device shown by FIG.16;

FIG. 18 is a schematic view of a typical utilization device for thesignal derived by the load measuring device;

FIG. 19 is a view similar to FIG. 12, but of only the codend, thefunnel, and small portions of the net side elements, such view showing amodified arrangement of the load sensing apparatus, involving a loadmeasuring device mounted on the lower suspension assembly;

FIG. 20 is a view similar to FIG. 13, but of the modified arrangementshown by FIG. 19;

FIG. 21 is a view like FIG. 19, but of still another modifiedarrangement of the load sensing apparatus, involving a load measuringdevice mounted on a mid line, representing a component of the net towingmeans, with a section of the mid line, which mid line extendssubstantially vertically below the load sensing line means duringtrawling, being offset to one side of the load sensing line means forclarity of illustration; and

FIG. 22 is a view like FIGS. 13 and 20, but of the arrangement of FIG.21.

Referring more specifically to FIG. 1, the trawl net assemblyillustrated thereby includes a trawl door 10 at each side of a net N,which doors are dragged forwardly by towing warps 12 extending aft froma trawler. The doors 10 spread apart net side members or curtains 14which depend from curtain lines 16. The after ends of curtains 14connect to the upper mesh panel 18 of a funnel 20, which extends aft andmerges into the codend 22. The funnel 20 and codend 22 together form thebody of the net. Suspenders 24 constructed of mesh material are locatedon each side of and in effect constitute parts of the funnel 20. Attheir respective forward ends the suspenders 24 are each gatheredtogether and formed into loops by which they are secured to therespective ends of a transverse suspension bar 26. Through thesuspension bar 26 and several connector elements the for- Ward or loopedends of the suspenders 24 are connected each with a separate sweep lineSL which extends forwardly of the net and is anchored onto one of thedoors 10. The sweep lines SL through the suspenders 24 assume the majorportion of the drag of the codend 22 and its catch. A transverse bobbinline 23 extends in front of the suspension bar 26 and at intervals alongits length, in between the bobbins 30, is suitably joined to thesuspension bar 26. Bobbins 30 rotate on bobbin line 28 while the net isbeing dragged over the bottom. A suitable bobbin assembly is describedin detail in my U.S. Patent No. 3,121,968, issued Feb. 25, 1964. Thestructural relation of the suspenders 24 to the funnel 20 is fullydisclosed in, and in part forms the subject matter of, my allowedcopending application Ser. No. 259,230, filed Feb. 18, 1963, now PatentNo. 3,188,765, and entitled Trawl Net Construction.

FIGS. 2-11 show in detail a typical pursing or closure mechanism for theoutlet to the codend, together with the after portion of the load linemeans, hereinafter to be described in detail. As perhaps best shown inFIGS. 8-11, a plurality of eyes or eye rings 32 are distributed aboutthe rear end opening of the codend 22 and are secured to the codend bymeans of a ring line 34 woven alternately through a ring 32 and thenthrough several of the meshes defining the outlet opening, as shown byFIG. 8, for example. A purse line 36 extends successively through therings 32 and serves as the means by which the meshes at the rearterminal of the codend may be gathered together so as to close the rearend of the codend 22. The purse line 36 may include a section of chain36' and a codend lock and release mechanism 38 of the type disclosed inand forming the subject matter of my US. Patent No. 3,044,206, issuedJuly 17, 1962. For a more detailed description of the structural makeupand operation of the typical and therefore non-limitive form of codendclosure mechanism that is illustrated, reference is made to such PatentNo. 3,044,206.

An anchor line 40 also extends successively through the eye rings 32.Line 36 is substantially equal to the circumference or perimeter of theopen outlet opening. A load sensing line means is connected to the afterterminal of the codend by the line 40. The load sensing line means thenextends forwardly of the codends after terminal, through the interior ofthe codend 22, and is connected at its forward end to a load sensingdevice LS which is preferably mounted on a portion of the towing meansfor the net,'either aft or rearwardly of the doors 10. The load sensingdevice will hereinafter be described in detail.

The rear portion of the load sensing line means preferably comprises abridle 42 consisting of a plurality of bridle members 44 which areshackled or otherwise secured together at their forward ends and aresecured at their after ends to the rear terminal of the codend 22 bymeans of the line 40. Preferably, the bridle members 42 consist of shortlengths of light chain, and the line 40 extends through the last link 46of each such member 44.

When the purse line 36 is drawn tight so as to close the outlet opening,slack is developed in both line 34 and line 40. During trawling the loadsensing line means is in tension and exerts a pull on these lines 34,40, pulling them into a sinuous shape (FIGS. 2, 3, 8 and 10, forexample).

In the preferred form of the invention the forward ends of the bridlemembers 44 are gathered together and connected, as by a pair of shacklesS1, S2, to the rear terminal of a relatively short length of a smalldiameter wire rope or cable 47. Preferably, a section 48 of highstrength elastic material, such as a piece of rubber having thenecessary tensile strength, for example, is connected to and extendsforwardly of the line 47. At its forward end the elastic member 48 isconnected to the after ends of a pair of small diameter lines 50, 52which diverge apart as they extend forwardly, each to a different one ofthe doors 10. One of such lines 50, 52, say line 52, for example, ismerely connected to its door 10. The load sensing device LS is locatedon the opposite door 10, and the forward end of line 50 is connected tosaid load sensing device LS, as will now be described.

The load sensing device LS may assume various forms. The typical andtherefore nonlimitive embodiment of such a device (FIGS. 14 and 15)comprise a rocker arm 54 provided at one end with a shackle 56connecting it to the forward end of the line 50. The opposite end of therocker arm 54 is pivotally connected to the end of a piston rod 58. Apiston 60 carried by the piston rod 58 is received in a hydrauliccylinder 62. The cylinder 62 is designed to withstand the pressuresgenerated internally and externally and is provided with a side port 64which communicates with the interior of a hydraulic pressure sensingelectrical transducer device 66. The rocker arm 54 is pivotally mountedby mean of a relatively short, fixed shaft 68 which is secured to amounting plate 70. The mounting plate 70 is in turn suitably secured tothe door 10.

When tension develops in the line 50, the rocker arm 54 tends to rotatein the counterclockwise direction (as viewed in FIGS. 14 and 15 but itsturning is resisted by the hydraulic fluid present in the cavity 72.Slight movement of the rocker arm 54 does occur, however, causing thepiston 60 to move against and increase the pressure of the hydraulicfluid. This increased hydraulic pressure is transmitted through the port64 to the interior of transducer device 66 wherein it actuates a means(not shown) to convert pressure into an electrically detectable signal.A Bourbon tube, diaphragm, or other means responsive to hydraulicpressure and actuating a potentiometer or piezoelectric detector, arerepresentative of transducer arrangements which may be employed.

Preferably the piston rod 58 extends through an opening in the end ofcylinder 62 opposite the rocker arm 54. By virtue of this arrangementthe water pressure on the piston rod 58, and hence on the rocker arm 54,are equalized.

An electrical conductor extends inwardly from the transducer device 66through a watertight conductor 74 preferably to a watertight electricalconnection 76 secured to the door 10.

Referring now to FIGS. 14, 16 and 17, a towing warp bridle 76 stands outfrom the door on its anterior side and is connected to a towing warp 12by means of a shackle 78, preferably of the type disclosed in and inpart forming the subject matter of my aforementioned application Ser.No. 305,485.

Referring now to FIGS. 16 and 17 in particular, the shackle 78 comprisesan elongated tubular member 80 through which the towing warp 12 extends.The towing Warp 12 has as a core an electrical cable 82 which comprisesone or more insulated electrical conductors. The towing warp 12 isswaged on to the tubular member 80 or is otherwise secured thereinagainst relative longitudinal movement. The shackle 78 also includes agenerally -shaped clevis type member 84 having apertured ends 86 and abight portion 88. A flange and headed grommet 90 extends through theaperture in each end portion 86 and bears against one side of a relatedone of a pair of bosses 92 formed on opposite sides of and intermediatethe ends of tubular member 80. These grommets 90 are secured in place bymeans of bolts 94, or the like, which thread into internally threadedopenings formed in the bosses 92. Wear washers 96 may be interposedbetween the inboard side surfaces of the end portions 86 and adjacentsurfaces of the bosses 92.

Rearwardly of the bolts 94 the tubular member 80 curves outwardly so asto direct the cable 82 away from the clevis member 84 which, in itsnormal load position, is in a plane aligned with the direction of extentor pull of the towing warp 12 (FIG. 16).

A terminal fitting 98 is provided at the extreme rear end of electricalconductor 82, and such fitting mates and forms a watertight connectionwith a complementary fitting 76 on the door into which the conduit 74and the electrical conductor therein extend.

As schematically shown by FIG. 18, the towing warp 12 is wound onto awinch drum 102 situated aboard the trawler T (FIG. 12). The coreconductor 82 immerges from the winch drum 102, as by means of a brushand slip ring arrangement (not shown), for example, and extends to aload detector 164 which may comprise an electrical amplifier bridgecircuit, or other electrically responsive device. The output of the loaddetector 104 may be applied to a load indicator and/ or recorder 106which indicates and/or records for the benefit of the operator theexisting load condition in the load sensing line means 42, 47, 48, 50,52.

Referring back to FIGS. 2 and 3, and to FIGS. 12 and 13, the loadsensing line means 42, 47, 48, 50, 52, is intentionally designed to beshorter fore and aft than the distance rearwardly from a point on thecenterline of the net in a common transverse plane with the point ofconnection of the forward end of line 50 to the rocker arm 54, and ofthe line 52 to the opposite door 10', rearwardly to the position whichthe pursed after terminal of the codend 22 would take if the net endwere to be fully distended and the load line means 42, 47, 48, 5t 52were to be unattached. This is illustrated in FIG. 12. Point P1represents the point on the centerline C/L of the net N which is in acommon transverse plane with point P3 representing the point ofconnection of the line 50 with rocker arm 54, and point P2, representingthe point of connection of line 52 with the port side door 15 Point P4represents the position which would be occupied by the pursed rearterminal of the codend 22 during trawling if the load sensing line means42, 47, 48, 50, 52, where not attached. Point P5 represents the positionwhich the pursed rear terminal does occupy with said load line sensingmeans 44, 47, 48, 50, 52 attached.

As shown quite clearly in FIGS. 2 and 3, this length differential causesthe rear portion of the codend to be turned outside in during trawling.As shown in FIG. 3, this gives the codend what may be termed asemi-toroidal shape rearwardly of the internal position of the pursuedterminal of the codend 22. This arrangement also causes the formation ofan annular rear wall 108 of mesh for the codend 22.

When the net end is being towed through the water empty, the watermoving relatively past the wall 108 resses against and hence exerts arearwardly directed force on the strands of twine making up the wall 108of mesh. As fish enter and tend to fill up the codend 22 they also pressagainst the rear wall 108. The forces produced by the water and fish inthe net pressing against the rear wall 108 represents a portion of thetotal drag of the net and its load, and it is this portion of the totaldrag that is measured by the load sensing equipment of the presentinvention.

Referring again to FIG. 3, as will be evident, a force F1 pushingrearwardly on wall 168 will cause tension to be put into the loadsensing line means 42, 47, 48, 50, 52, whereas a force F2, pushingrearwardly on the portion of codend 22 situated forwardly of wall 108(or on any other part of the net assembly forwardly of the codend 22)would not put tension in the load sensing line means 42, 47, 48, 50, 52.This is because, with the exception of the greater portion of wall 168,the component parts of the net, commencing with the portion of thecodend 22 situated immediately forwardly of the wall 108 and proceedingforwardly to the doors 16, are connected to the doors 10 by the curtainlines 16 and the sweep lines SL in a maner such that the drag producedby those components of the net result in tensioning of the curtain 7line 16 and sweep lines SL, but not of the load sensing line means 42,47, 48, t), 52.

It will also be appreciated that the drag attributed to water and fishin the net pressing rearwardly against the wall 108, which drag is beingsensed and measured by the load sensing equipment of the presentinvention, is relatively small in comparison to the drag produced by theentire net, and smaller yet in comparison to the drag produced by allcomponents in the water rearwardly of the trawler, including, inaddition to the net N, the lines 16, SL, the doors 1t) and the towingwarps 12.

As will be evident, there is a direct relationship to the amount of fishin the codend 22 and the magnitude of the force directed rearwardlyagainst wall 198. Thus, when the signal based on the tension in the loadsensing-line means 42, 47, 48, 50, 52 (representing the force actingrearwardly against wall 1&3) is received aboard the trawler, it can beused to give a reliable indication as to the quantity of fish in the netN. The dial of the indicator 1% may be designed so as to indicate themagnitude of the force in the load sensing line means 42, 47, 48, 5t 52,or may be designed to give a direct reading as to the pounds of fish inthe net.

As previously mentioned, even when the net is empty, there will be sometension put in the load line sensing means 42, 47, 48', 50, 52 by virtueof water pressing rearwardly against the wall 1nd. The dial of theindicator device 136 may be made so that it can be set to a new zeroreading after the net is set and the drag force on wall 108 when thecodend 22 is empty is determined and recorded. Any additional drag thatwould then be indicated on the dial above zero would be attributedsolely to fish in the net pressing rearwardly against the wall 108.

The magnitude of the force produced by fish in the net pressingrearwardly against the wall 108 (the level of a catch of fish, e.g.,shrimp, is indicated by the broken line B in FIG. 3, for example) isrelatively large in comparison with the force produced by water alonepressing against the wall 108. Also, the maximum total forces which needbe measured by the load sensing equipment of the present invention isrelatively small in comparison with the maximum total force that wouldhave to be measured if the load sensing equipment were attached to thetowing warps 12 and the drag of the entire net assembly were to bemeasured, much in the manner disclosed in the aforementioned DlntinoPatent No. 2,513,153. For these reasons the increase in force attributedto fish in the net can be reliably and very accurately sensed. Since thetotal forces involved are relatively small, the indicating and/orrecording device 1% need only be capable of measuring a relatively smallmaximum force. Each increment of force measured reprfesents only a smallamount of additional drag. Thus, slight increases in drag can bemeasured, with the result being that the trawler operator is given areliable reading which is not overshadowed by a relatively largeconstant drag (i.e., the load of the entire net N, the lines 16, SL, thedoors and the towing warps 12).

As will be evident, the line sensing line means itself produces a-slightamount of drag. However, the value of its share of the drag sensed issmall in relation to the whole, and allowance can be easily made for itat the utilization equipment.

After the doors 10 and the net N are brought aboard the trawler T,tension is taken out of all of the net components, including the loadsensing line means 42, 47, 48, 50, S2, and the codend lock and releasemechanism 38 is tripped or unlocked so that the rear of the codend 22 isopened and the catch may be emptied from the net N.

According to the invention, the reason bridle members 44 are made out ofchain is so that such members 44 are flexible and can easily be handledduring the procedure of opening the codend and dumping the catch. Ifcable were to be used in place of the chain, the members 44 would berelatively stiff and hard to handle.

The elastic section 48 of the load sensing line means is provided forthe purpose of relieving some of the tension in such line means, makingit possible to make the lines 47, 5t), 52 from relatively small diametercable. It is preferred that lines 47, 50, 52 be constructed frommultiple strands of stainless steel wire that is approxi* mately {o, ofan inch in diameter.

*FIGS. 19-22 relate to modified arrangements of the load sensingequipment according to the present inven tion. In FIGS. 19 and 20 theload sensing device LS is shown attached to one end of the bobbinassembly. This can easily be done by mounting all parts of such loadsensing device LS onto a mounting plate, similiar to mounting plate 7t)shown in FIG. 15, and then this mounting plate may be secured to the endof the bobbin line 28. A first elastic member 48' extends rearwardlyfrom the rocker arm portion of the load sensing device LS to the forwardend of line 47, and a second elastic member 48" extends rearwardly fromthe opposite end of the bobbin line 28 to such forward end of the line47. In this form of the invention the conductor 82 extends forwardlyfrom the load sensing device LS directly to the trawler, independent ofthe towing warp 12.

In the arrangement shown by FIGS. 21 and 22, a mid line ML is providedwhich extends rearwardly from the trawler T and connects to the oppositeends of the bobbin line 28. Such mid line ML is a part of the towingmeans for the net assembly. In this form of the invention, the sensingdevice LS is mounted on the mid line ML at a location ahead of thebobbin line 28. As before, this may be done by mounting all of thecomponents of such load sensing device LS onto a mounting plate similarto plate 70 in FIG. 15, and then connecting such mounting plate to themid line ML. Line 50' is connected at its forward end to the rocker armportion of the load sensing device LS and at its after end to theforward end of the elastic member 48. As before, the after end 48 isattached to the forward end of a line 47 leading rearwardly to thepursed after terminal of the codend 22.

From the foregoing, further variations, adaptations, modifications andcharacteristic features can be evolved by those skilled in the art towhich the invention is addressed within the scope of the followingclaims.

What is claimed is:

1. In combination with a forwardly open trawl net including a codendhaving a closed after end portion, and towing means connected to andextending forwardly of said net to a trawler, means for determining thepresence and quantity of fish in said net, said means comprising: loadsensing line means connected to and extending forwardly of said codend;load sensing means connected to said load sensing line means, said loadsensing means serving to measure the amount of tension put into saidload sensing line means by reason of water and fish in the net pressingagainst the after end portion of said codend as the net is towedfor-wardly, and to derive a signal based on such amount of tension,which signal is indicative of the quantity of fish in the net; means fortransmitting said signal to the trawler; and means on the trawler forreceiving and utilizing such signal.

2. The combination of claim 1, wherein the said towing means includes atleast one trawl door situated forwardly of and connected to said net,between the net and and the trawler, and wherein the said load sensingmeans is mounted on said trawl door.

3. The combination of claim 1, wherein said towing means includes asuspension means for an intermediate portion of said net, and whereinsaid load sensing means is connected to said suspension means.

4. The combination of claim 1, wherein the towing means includes midline means connected to and extending forwardly of said net to thetrawler, and wherein the said load sensing means is mounted on said midline means.

5. The combination of claim 1, wherein the load sensing line meanscomprises a relatively small diameter line and a resilient lineconnected thereto.

6. 'In combination with a trawl net that is open in the forwarddirection and has a pursed after terminal, and towing means connected toand extending forwardly of said net to a trawler, means for determiningthe presence and quantity of fish in said net, said means comprising:load .sensing means mounted on a portion of said towing means forwardlyof said pursed terminal; load sensing line means interconnecting betweensaid load sensing means and the pursed terminal, said load sensing linemeans being shorter than the distance between the load sensing means andthe pursed terminal when the net is fully distended and said loadsensing line means is unattached, so that during trawling, when the loadsensing line means is attached, the after end portion of the net ispulled outside in by the load sensing line means and assumes a generallysemi-toroidal shape, and forms an annular rear wall of mesh for the net,with said load sensing means serving to measure the amount of tensionput into said load sensing line means by reason of water and fish in thenet pressing against said annular rear wall of mesh, and to derive asignal based on said amount of tension, which signal is indicative ofthe quantity of fish in the net; means for transmitting said signal tothe trawler; and means on the trawler for receiving and utilizing suchsignal.

7. The combination of claim 6, wherein the load sensing line meansincludes a bridle comprising a plurality of leg members secured at theirafter ends to said purse-d terminal and coming together at their forwardends, and a line connected to and extending forwardly from said forwardends to said load sensing means.

8. The combination of claim 6, wherein the load sensing line meanscomprises a relatively small diameter line and a resilient lineconnected thereto.

9. In combination with a forwardly open trawl net having a pursed afterterminal and a generally transverse after wall, load sensing equipmentcomprising: load sensing line means attached at its after end to thepursed terminal, and load measuring means, including a strain gauge towhich the forward end of said load sensing line means is attached, formeasuring the tension put in said load sensing line means by water andfish in the net.

10. In a trawl net, a forwardly opening cOden-d of netting including arear outlet opening, a plurality of eyes distributed about said rearoutlet opening, a purse line extending through said eyes and encirclingsaid outlet opening, to be drawn tight or alternatively to be relaxed, aconnector line extending through at least some of said eyes andencircling said outlet opening, a bridle comprising a plurality of legmembers having rear terminii secured at intervals along said connectorline, said leg members extending forwardly from said line, through theinterior of said codend, and having forward terminii which are joinedtogether at a location inside said net and a load sensing line connectedto and extending forwardly of said forward te-rminii of the leg membersto means for measuring tension therein.

11. The combination of claim 10, wherein the said leg members of thebridle each consist of a relatively short length of chain.

12. The combination of claim 10, wherein said eyes distributed about therear end opening each consists of a metallic ring secured to a portionof the netting which borders the outlet opening.

13. The combination of claim 10, wherein the connector line is endlessand of a length that is at least slightly larger than the circumferenceof the outlet opening when the purse line is relaxed and the nettingimmediately surrounding and defining the outlet opening is fullydistended.

References Cited UNITED STATES PATENTS 354,763 9/1886 Bartlett 43141,152,081 8/1915 Dingwell 4314 2,609,181 9/1952 Jaeschke 2541722,723,481 11/1955 Swartz 437 OTHER REFERENCES Modern Fishing Gear of theWorld published 1959 by Fishing News Ltd., London, England, pages 228,229 and 233.

ALDRICH F. MEDBERY, Primary Examiner.

SAMUEL KOREN, WAR'NER H. CAMP, Examiners.

